The present invention concerns the treatment of endothelial cell injury. More particularly, the invention concerns the treatment of the endothelium of blood vessels and tissues containing injured blood vessels. The invention specifically concerns the prevention or repair of injury to blood vessels, and, in particular, the treatment of disorders characterized by microvascular angiopathies, such as thrombotic microangiopathies (TMA). The invention also relates to the treatment of kidney diseases associated with injury to, or atrophy of, the vasculature of the glomerulus and interstitium, and the treatment of hypoxia or hypercapnia or fibrosis arising from injury to the endothelium of the lungs.
Acute injuries to smaller blood vessels and subsequent dysfunction of the tissue in which the injured blood vessels are located (microvascular angiopathies) are a common feature of the pathology of a variety of diseases of various organs, such as kidney, heart, and lungs. The injury is often associated with endothelial cell injury or death and the presence of products of coagulation or thrombosis. The agent of injury may, for example, be a toxin, an immune factor, an infectious agent, a metabolic or physiological stress, or a component of the humoral or cellular immune system, or may be as of yet unidentified. A subgroup of such diseases is unified by the presence of thrombotic microangiopathies (TMA), and is characterized clinically by non-immune hemolytic anemia, thrombocytopenia, and/or renal failure. The most common cause of TMA is the hemolytic uremic syndrome (HUS), a disease that more frequently occurs in childhood, where it is the most common cause of acute renal failure, but also affects adults where more severe clinical course is often observed. Although the pathogenesis of HUS has not been fully elucidated, it is widely accepted that the majority of these cases are associated with enteric infection with the verotoxin producing strain, E. coli O157. Verotoxins produced by E. coli induce glomerular. endothelial cell (GEN) injury and generate renal thrombotic microangiopathy in most cases of epidemic HUS (Boyce et. al., N. Engl. J. Med. 333:364-368 (1995)). Some patients, especially adults, may have a relative lack of renal involvement and are sometimes classified as having thrombotic thrombocytopenic purpura (TTP). However, thrombotic microangiopathies may also occur as a complication of pregnancy (eclampsia), with malignant hypertension following radiation to the kidney, after transplantation (often secondary to cyclosporine or FK506 treatment), with cancer chemotherapies (especially mitomycin C), with certain infections (e.g., Shigella or HIV), in association with systemic lupus or the antiphospholipid syndrome, or may be idiopathic or familial. Experimental data suggest that endothelial cell injury is a common feature in the pathogenesis of HUS/TTP. See, e.g. Kaplan et al., Pediatr. Nephrol. 4:276 (1990). Endothelial cell injury triggers a cascade of subsequent events, including local intravascular coagulation, fibrin deposition, and platelet activation and aggregation. The mechanisms that mediate these events are not well understood. In the case of verotoxin-mediated HUS, injury to the endothelium leads to detachment and death, with local platelet activation and consumption, fibrin deposition and microangiopathic hemolysis.
The renal corpuscule, commonly referred to as glomerulus, is composed of a capillary network lined by a thin layer of fenestrated endothelium; a central region of mesangial cells with surrounding mesangial matrix; the visceral epithelial cells and the associated basement membrane; and the parietal layer of Bowman capsule with its basement membrane. Between the two epithelial layers, there is a narrow cavity called the urinary space. The glomerulus is responsible for the production of an ultrafiltrate of plasma. The endothelial cells form the initial barrier to the passage of blood constituents from the capillary lumen to the urinary space. Under normal conditions, the formed constituents of the blood, such as erythrocytes, leukocytes, and platelets, do not gain access to the subendothelial space. In addition, because of their negative surface charge, the endothelial cells contribute to the charge-specific properties of the glomerular capillary wall. In the kidney, the damage to the glomerular and peritubular capillaries and arterioles results in ischemia and acute tubular necrosis, and, if severe, may lead to patchy or regional cortical necrosis. For further details see also Brenner and Rector""s: The Kidney, Fifth Ed., Barry M. Brenner ed., W. B. Saunders Co., 1996.
The current treatment of HUS in children consists primarily of supportive therapy (dialysis, transfusions and attention to fluid and electrolyte balance). However, in adults and in refractory cases in children the addition of plasma infusion and/or plasma exchange therapy is also performed. Remuzzi and Ruggenenti, Kidney Int. 47:2-19 (1995). Data to support plasma exchange therapy is not conclusive, but uncontrolled trials have suggested a potential benefit, especially in terms of improving the thrombocytopenia, anemia, and associated neurologic signs (which consist of confusion, paresthesias, and occasionally coma). Most patients recover from the acute episode, although mortality rates of 3-8% are occasionally reported. Brandt and Avner, Hemolytic uremic syndrome and thrombotic thrombocytopenia purpura. In: Neilson and Couser, eds., Immunologic Renal Diseases, Lippincott-Raven, Philadelphia, 1996, pp. 1161-1181. However, some patients do not recover their renal function fully, and between 20 and 40% of patients will develop some degree of renal impairment or hypertension within 10-15 years, with as many as half progressing to dialysis. Brandt and Avner, supra. In 1995, HUS accounted for 2.4% of patients on dialysis. Patients at risk were those with greater than 50% glomerular involvement, arteriolar disease, or cortical necrosis. Habib et al., Adv. Nephrology 11:99-128 (1982).
There is a great need for new therapeutic agents for the treatment of microvascular angiopathies, and in particular, thrombotic microangiopathies (TMA). There is a particular need to find a way to preserve cells and maintain normal function of organs within which the blood vessels are undergoing, or have undergone, injury. Currently, no therapy has been proposed for the treatment of microvascular angiopathies that is targeted at preventing or reducing endothelial cell injury and stimulating the repair of injured endothelial cells. Indeed, most of the agents in clinical use are either aimed at removing or infusing unknown factors (plasma exchange/plasma infusion), inhibiting platelet action (antiplatelet drugs), or blocking the immune system (steroids and vincristine).
There is further a need for new approaches to the treatment of renal diseases involving injury to the glomerular endothelium and the tissues surrounding the injured glomerular blood vessels, and in particular, the treatment of hemolytic uremic syndrome (HUS).
The present invention concerns compositions and methods for the prevention or reduction of endothelial cell injury, or the repair of endothelial cells already injured. While the repair of injured endothelial cells might be accompanied by the formation of new blood vessels (angiogenesis), angiogenesis is not considered to be the primary mechanism of the treatments according to the present invention.
In one aspect, the invention concerns a method for the prevention or repair of injury to blood vessels by administering an effective amount of an angiogenic factor or an agonist thereof, or a factor stimulating the production of an angiogenic factor. In a particular embodiment, the injury is associated with microvascular angiopathy, such as thrombotic microangiopathy (TMA). In a further embodiment, the invention concerns the treatment of microvascular angiopathy, e.g. TMA of the kidney, heart, or lungs. In a particularly preferred embodiment, the invention concerns the prevention or repair of injury to blood vessels in association with hemolytic uremic syndrome (HUS), including thrombotic thrombocytopenic purpura (TTP).
In a particular embodiment, the invention concerns a method for the prevention or repair of injury to vascular tissue in combination with other therapies directed at the etiology or vascular injury, such as antibiotics, corticosteroids or other immunosuppressants, anti-cancer agents, plasma exchange, clot dissolving agents, etc.
In another aspect, the invention concerns a method for the prevention or repair of injury to nonvascular tissue associated with injury to blood vessels serving the tissue, by administering an effective amount of an angiogenic factor or an agonist thereof, or a factor stimulating the production of an angiogenic factor. The treatment preferably maintains the normal function of the organ comprising the nonvascular tissue, such as kidney, heart, or lungs.
In a further aspect, the invention concerns a method for the treatment of hemolytic uremic syndrome (HUS) by administering to a patient at risk of developing or having diagnosed HUS an effective amount of an angiogenic factor, or an agonist thereof, or a factor stimulating the production of an angiogenic factor.
In yet another aspect, the invention concerns a composition for the prevention or repair of injury to blood vessels comprising an effective amount of an angiogenic factor or an agonist thereof, or a factor stimulating the production of an angiogenic factor, in admixture with a carrier.
In a still further aspect, the invention concerns a composition for the prevention or repair of injury to nonvascular tissue associated with injury to blood vessels serving said tissue comprising an effective amount of an angiogenic factor or an agonist thereof, or a factor stimulating the production of an angiogenic factor, in admixture with a carrier. The composition may optionally contain one or more further agents effective in therapies directed at the etiology of vascular injury, such as antibiotic, corticosteroid, or other immunosuppressants, anti-cancer agent, clot dissolving agent, etc.
The invention also concerns an article of manufacture comprising a
container,
a composition within the container comprising an angiogenic factor or an agonist thereof, or a factor stimulating the production of an angiogenic factor, and
instructions to use the composition for the prevention or repair of injury to blood vessels.
The invention further concerns an article of manufacture comprising a
container,
a composition within the container comprising an angiogenic factor or an agonist thereof, or a factor stimulating the production of an angiogenic factor, and
instructions to use the composition for the prevention or repair of injury to nonvascular tissue
associated with injury to blood vessels serving said tissue.
In yet another aspect, the invention concerns an article of manufacture comprising a
container,
a composition within the container comprising an angiogenic factor or an agonist thereof, or a factor stimulating the production of an angiogenic factor, and
instructions to use the composition for the treatment of hemolytic uremic syndrome (HUS).
In a different aspect, the invention concerns a method for the prevention or repair of injury to vascular endothelial cells, comprising introducing into such endothelial cells a polynucleotide encoding an angiogenic or cytoprotective factor, an agonist thereof, or a factor stimulating the production of an angiogenic or cytoprotective factor.
In a further aspect, the invention concerns a method for the prevention or repair of injury to nonvascular tissue associated with injury to blood vessels serving such tissue, comprising introducing into such nonvascular tissue a polynucleotide encoding an angiogenic factor, an agonist thereof, or a factor stimulating the production of an angiogenic factor.
In all aspects and embodiments, the angiogenic factor may, for example, be a vascular endothelial growth factor (VEGF), or a basic or acidic fibroblast growth factor (bFGF or aFGF). The VEGF preferably is hVEGF121 or hVEGF165, which may, for example, be in homo- or heterodimeric form, and may be partially or fully unglycosylated. The angiogenic factors, such as VEGF, preferably exert their activity primarily via effects other than inducing new blood vessel formation.